Fear of pain and event-related potentials during exposure to image-cued somatosensory stimulation

Electrocortical activity associated with movement-related fear: a methodological exploration of a threat-conditioning paradigm involving destabilising perturbations during quiet standing

Musculoskeletal trauma often leads to lasting psychological impacts stemming from concerns of future injuries. Often referred to as kinesiophobia or re-injury anxiety, such concerns have been shown to hinder return to physical activity and are believed to increase the risk for secondary injuries. Screening for re-injury anxiety is currently restricted to subjective questionnaires, which are prone to self-report bias. We introduce a novel approach to objectively identify electrocortical activity associated with the threat of destabilising perturbations. We aimed to explore its feasibility among non-injured persons, with potential future implementation for screening of re-injury anxiety. Twenty-three participants stood blindfolded on a translational balance perturbation platform. Consecutive auditory stimuli were provided as low (neutral stimulus [CS-]) or high (conditioned stimulus [CS+]) tones. For the main experimental protocol (Protocol I), half of the high tones were followed by a perturbation in one of eight unpredictable directions. A separate validation protocol (Protocol II) requiring voluntary squatting without perturbations was performed with 12 participants. Event-related potentials (ERP) were computed from electroencephalography recordings and significant time-domain components were detected using an interval-wise testing procedure. High-amplitude early contingent negative variation (CNV) waves were significantly greater for CS+ compared with CS- trials in all channels for Protocol I (> 521-800ms), most prominently over frontal and central midline locations (P ≤ 0.001). For Protocol II, shorter frontal ERP components were observed (541-609ms). Our test paradigm revealed electrocortical activation possibly associated with movement-related fear. Exploring the discriminative validity of the paradigm among individuals with and without self-reported re-injury anxiety is warranted.

The overgeneralization of pain-related fear in individuals with higher pain sensitivity: A behavioral and event-related potential study

Fear generalization contributes to the development and maintenance of pain. Pain sensitivity has been proposed to predict the strength of fear responses to aversive stimuli. However, whether individual variation in pain sensitivity affects pain-related fear generalization and its underlying cognitive processing remains unclear. To address this gap, we recorded behavioral and event-related potential (ERP) data among 22 high pain sensitivity (HPS) and 22 low pain sensitivity (LPS) healthy adults when exposed to a fear generalization paradigm. The behavioral results indicate that the HPS group displayed higher unconditioned stimulus expectancy and greater fear, arousal, and anxiety ratings to conditioned stimulus and generalization stimulus than the LPS group (all p values < 0.05). The ERP results showed that the HPS group exhibited a larger late positive potential evoked by GS2, GS3 and CS- (all p < 0.005) but a smaller N1 evoked by all CS and GSs (all p values < 0.05) relative to the LPS group. These findings suggest that individuals with a high level of pain sensitivity allocate more attention resources to pain-related threatening stimuli, which contributes to an overgeneralization of pain-related fear.

The linkage between first-hand pain sensitivity and empathy for others' pain: Attention matters

Many studies suggested shared psychological and neural representations for first-hand physical pain and empathy for others' pain, both of which depend strongly upon top-down controlled mechanisms such as attention. This study aimed to assess the interindividual variation in first-hand physical pain and empathy for pain, and whether their relationship is dependent upon attention. We recruited participants exhibiting high and low sensitivity to first-hand pain (HPS and LPS), and adopted pain empathy paradigms involving attention directed toward or withdrawn from pain of another. Relative to the LPS group, participants in the HPS group estimated greater pain intensity experienced by others, felt greater unpleasantness when viewing others in pain, and exhibited greater sensitivity in discriminating others' pain. Electroencephalographic data showed that when attention was directed toward others' pain, only participants in the HPS group exhibited significant pain empathic effects on the N1 component of event-related potentials and on the α-oscillation response. These empathic neural responses mediated the linkage between first-hand pain sensitivity and empathic behavioral responses. Nevertheless, empathic responses were comparable between two groups when attention was withdrawn from others' pain. These results demonstrate a shared sensitivity to first-hand pain and empathy for pain provided that attention is directed toward pain.